Absorption refrigerating system



Sept 20, 1932. s R CUMNHNGS ,878',83

ABSORPTION REFRIGERATING SYSTEM Filed Jan. 24. 1930 2 Sheets-Sheet lSept. 20, '1932. s, R CUMM|NGS ,878,83l

ABSORPTION REFRIGERATING SYSTEM Filed Jan. 24. 1950 2 Sheets-Sheet 2 5w22 I ILL Patented Sept. 20, 1932 UNITED .STATES P STANLEY B. CUMMINGS,OF CANTON, OHIO, ASSIGNOR TO THE HOOVER NORTH C ANTON, OHIO, .ACORPORATION OF OHIO nsonrrron REFBIGERATING- SYSTEM ApplicationvledJanuary 24,- 1930. Serial No. l1223,075.

This invention relates to the art ofV refrig-"l erating and moreparticularly ,to an absorption refrigerating system in which a pluralityof refrigerants are simultaneously evaporated to produce a coolingefect.

` Continuousv absorption refrigerating systems employing a singlerefrigerant in combination with an inert or neutral gas are well known."In such a systemv the inert gas is circulated between the evaporatorand the absorber for the purpose of maintaining the tot'al pressure inthese parts the same as that in the other parts of the system althoughthe partial pressure of the refrigerant changes.

Anexample of such a system is found in the U. S. Patent to Geppert662,690. As an improvement on this system is has previously beenproposed to substitute a second refrigerating agent for the inert gas ofthe Geppert system so that both the main cooling agent and the auxiliarypressure.equalizing agent may be`condensed before they are introducedinto the evaporator, the object being to increase the eiiiciency andthecooling effect of the system. Perhaps the best substances suggested forthis purposevare ammonia and propane, these two refrigerants beingcondensable at about the same temperature and pressure and beingpractically immiscible.

In attempting to operate a system having two refrigerants, one of thechief diuculties encountered has resulted from the fact that it isdifficult if not impossible to completely separate the two so long asthey remain in a gaseous or vapor phase. Unless effectively nseparated,the refrigerants get into the condensers in which they do not belong andprevent successful operation of the apparatus.

An object of the present inventionis to provide effectivemeans forseparating the refrigerants of such a system so that each may becondensed independently at the pressure existing within the system andat temperatures which may be considerably above that prevailing intheevaporator.

A further object of the invention is to provide a practical refigeratingsystem employing a plurality of refrigerants and in which 60 all of thepartsare in` opencommunicatiqn with one another so that nearly the sametotal pressure prevails throughout the system, the refrigerants-mutuallycooperating to reduce .the partial pressure of each so that evaporationof both may take place to produce a cooling effect.

A further object is to provide a method of eectively separating thefluids of a refrigerating system so that they may be readily condensed.v

Other objects and advantages reside in certain novel arrangements andconstruction of parts'as will be apparent from the following descriptiontaken in connection with the accompanying drawings in .which Figure 1 isa diagram .of an absorption refrigerating system embodying certain novelfeatures and illustrating one form of apparatus made in accordance withthe principles of the invention and Figure 2 isa diagrammatic showing ofa modified form of system illustrating the principles of the invention.

Referring to Figure l of the drawings, the system is there shownas'consisting of agenerator or boiler G, rectifiers .R1 and densers C1and C2, evaporator E and an absorber-.separator S as essential elements,these vessels bein connected by suitable conduits, as shown.y ll-ofthese parts may be made of steel. In general, they are cylindrical inshape so thatordinaryseamless steel tubing may be used in manufacturingthem.

The generator G comprises a hollow shell -10 having end closures orheads 11 and-12 at the top and bottom thereof. The lower end piece 12 isprovided with an inverted cup 13 which is welded orotherwise secured toan opening therein and which is adapted to receive an electric cartridgeheating element 14. Obviously a gas flame or other heating means may beemployed in place of the electric heater. In normal operation, asolution of ammonia circulates through the generator. For conducting thesolution into the generator a pipe 15 extends through the wall or shell10 and is connected to a small coil of tubing 16 which is wrapped aroundthe inverted cup 13. The upper end of the coil 16 is connected to alsmall vertically extending COMPANY, or

2, conpasses through the electric heater l14, bubbles of ammonia gas aregenerated in the coil 16 and as-they rise through the pipe' 17 lift orpump the solution into the main body .of the generator, this actionbeing similar to that ound in certain types of household coffeepercolators. A similar arrangement of a gas lift pump of this nature ina refri'gerating system is shown and described in U. S. Patent toAltenkirch 1,728,742. j

Aside from the ammonia gas generated inl the gas lift pump, anadditlonal amountof gas may be driven oi by the application.` of heatfrom the electric heater to the main portion ofthe generator. The gas.passes upwardly through an openingin the closure 11 and into therectifier R1 which is provided with suitable baiiles, as shown, forremoving water vapor which is driven o with the ammonia.- vAn additionalamount of waterwapor is removed in the rectifier R2. This devieecomprises the central pipe 19 to which fins for radiating heat arewelded or otherwise secured. The upper end of rectifier R2 is connectedto condenser C1 through the pipe 21. A valve 22is provided in the pipe21- .which may be opened to charge the machine.

.As ammonia is driven off from the water, the weak ammonia solution -isconducted away from the generator through the conduit 23. The condensersC,L and. C2, referred to above, may be of any suitable construction.They are shown for the pur oses of illustration as consisting of coils otubing, the coil C2 being the larger of the two. The lcoils are immersedin a tank 24 through which cooling water is adapted to circulate, inletpipe 25 and outletpipe 26 being provided for this purpose. Since thecondenser C2 i-s the larger of the two, the temperature thereinwill bemore nearly that of the cooling water. The lower ends of thecondensersC]L and C2 are connected to the evaporator E by plpes 27 and28 each of which is provided withh a suitable valve.

The evaporator E' is so constructed that the liquids entering throughthe'pipes 27 and 28 do not mix so long as they are 1n the liquid phasebut each liquid is exposed to .the vapor phase of the other. Fora fulldisclosure of this evaporator reference may be had to .the copendingapplication of' Rudolph S. Nelson, Serial No. 423,125 filed Jan. 24,1930, entitled Evaporators for rev frigeratin systemslwherei'n thisevaporator is more ully disclosed and claimed. As herein shown itconsists of a cylindrical shell 29 having'end" pieces or heads 30 and 31at the upper and lower ends. The pipes 27 and 28 extend through the headpiece 30 and terminate a short distance above the bottom of cups 32which have overflow outletsnear their'upper ends.` Liquidsenteringthroilghthrough the conduit 33 extending through` the lower endpiece 31.

/An import-ant feature of the present invention resides in the`arrangement and construction of the absorber-separator vessel Stogether with means for cooling the lower por,- tion and heating theupper portion thereof.

Like the generator and evaporator the separator S is preferably composedof a` shell 35 provided with upper and lower end closures 36, 37. Thereare four conduits communi- 1eating with-the interior of this vessel.Conduit 33- passes through the wall of the shell j near its lower endfor connecting the vessel tothe evaporator. Conduit 38 having a valve 22therein similar to valve 22 4connects the upper end of the vessel to thecondenser C2. Condits 39 and 41 terminating at the bottom and side ofthe vessel respectively connect it with a heat exchanger 40.

v This heat exchan er is of the conventional double coil type.

ne endof the inner coil is connected to the pipe 39. The other end isconnected to the gas liftpump 16. The

outer tube of the heat exchanger. is connected to pipes 41 and 42. Thepipe 42 is adapted to convey solution into the heat exchanger from aheating jacket 44 surrounding the up"- per portion of the separator,this jacket being supplied with solution by the pipe 23. By thlsconstruction solution passing from the generator G through the conduit23 may heat the upper -portion of the separator by convection from thegenerator. Since it is likely that some as may collect in the jacket 44,it may be a visable to provide a bleed lpipe for conveying it back tothe generator.

A pipe for this purpose is shown at 43.

For coolin the lower portion of theaabsorber,`a jac et 45 is provided,this jacket having aconnection 46 for supplying cooling water thereto.From thejacket 45, the water goes through the pipe 25 to the tank 24.

For aiding inthe conduction of heat away from the lower portion of ytheseparator andl for facilitating the absorption of ammonia, the separatormay be partiallyy filled with steel wool-47 or other heat conductingmaterial adaptedt'o break up gases entering through the pipe 33 fromthev evaporator into small bubbles.v The steel wool may be held in placeby perforated plates 48.

The liquid levels in the .various parts ofl .the apparatus are criticallto successful operation of the machine. For this reason itis necessarythat the various parts be positioned approximately `as shown in thedrawings.

i vThis will more a :has filled the same up to approximately the parentafter considering the operation of the system.

The apparatus may ated as follows A quantity of ammonia solution isplaced in the 'generator G and separator S through suitable valves, notshown; until the same level ofpipe 23. While the concentration of theammonia solution may vary,` itgisv deemedadvisable to use one ofrelatively low concentration preferably not over 15% weight. Asthe'solutionis being placed -1n these vessels,

g phere so that air in the machine may escape.

A1nmonia the apparatus in the usual mannerto sweep out any remainingair. The valve 22may gas may thenbe forced through then beclosed andliquid-propane lfed into the conduit 38 through the valve 22 therein.This liquid propane collects in the separator and causes the solutionlevel in the generator to rise slightly but since propane has a specificgravity much lower than that of the ammonia solution, it'loatson top ofthe solution in the separator. The quantity of propane placed into thesystem should besomewhat more than that necessary to occupy the portionof the separator opposite the heating jacket 44 plus that necessarytolill one of thecups 32 andform a'column in the pipe 27, liquid propanenormally being in these parts to this extent during operation of thesystem.

- After `the machine is so charged heat may be applied to the generatorby causing current to pass through the electric heater. Thiscausescirculation ofthe ammonia solution and since the heatvexchangerand other pipes offer some resistance to iow, the liquid levels in thegenerator and separator assume the position approximately as shownindotted lines.- Ammonia vapor -orgasis delivered to the condenser C1and propane vapor is delivered to condenser C2. The heat necessary forthe evaporation of propane whichhas collected inthe upper portion of theseparator is supplied by the -warm ammonia solution circulating throughthe jacket 44. :Since the condensers C1 and C2 are maintained at atemperature considerably below that .of the boiler and upper, portion ofthe separator,

the two refrigerants condense in their re -vapor is much less. Asevaporation takes be charged and operi valves 22 and 22 in the con!duits 21 and 38'should be open to the atmosplace heat is -taken up fromthe surroundfings to produce a cooling' effect. At this time. `the totals 1 pressure inthe 'evaporator becomes htly larger than elsewhere in thesystem an 'causesthe formation of liquid columns in the pipes :27 land28 as the refrigerants continue to condense. Upon the pressure in theevaporatorv becoming large enough to overcome the slight excessvpressure due to vthe .liquid columnhead in theV separator bubbles ofammonia and propane are -forced into the lower portion of the separatorthrough lthe pipe 33. As these bubbles mix with the weak solution comingto the separator through the'pipe 41 the ammonia content'issab'sorbed,this causing an increase in 'the percentage of gaseous propane in thevbubbles andsince the bottom portion'of the separator is maintained coldby the cooling jacket 454 the propane "condenses at this point. As thepropane condenses it rises to the upper portion of the separatorwhere itis again driven oi by heatfrom the heating jacket 44 thus completing itscycle.

The ammonia whichis absorbed in the, solution in the lower portion ofthe separator is conducted through the pipes 39, the inner tube of. theheat exchanger 40` the plpe 15, gas lift pump 16 and pipe 17', backintothe generator where it lis again driven oil to complete its cycle.-

The solution thus deprived of ammonia returns to the separatorvthroughthe pipe 23,

'jacket 44, pipe 42., outer tube of heatex'- changer 40 and pipe j41.Effective separa-v tion of the'refrig'erants results from the novelfunctioning of the separator'. Iln refrig'en `atingsyste'ms heretoforeproposed employ ing-a plurality of refrigerants, extreme difficulty hasbeen encountered in separatlng the refrigerante so that they lmay beagaln condensed andfed into the evaporator in liquid form. Unless therefrigerants-are separated,the'apparatus cannot function to producerefrigeration for it is obvious that it gaseous ammonia collects in .thepropane conne 'A .denser C2 to the extent that thegasequsgmixturetherein is the same as that inthe evaporator'E then the propanecannotcondense in condenser C2 at a temperature higher than itevaporates in the evaporator. To obviate this diiiculty itis proposed.'in accordance with the present linvention, to separate the Jtworefrigerante by gravity and since they are practically immiscible inAtheir liquid phases very eflicient separation can be efcted in thismanner. But before they can be separated by gravity however, it is firstnecessary to reduce them-to their liquid phases. This iat isaccomplished in accordance with the inv vention, by causing lthe ammoniato be ab-` sorbed in a weak solution while at the'A same time the gasdeprived of a large portion of its ammonia contentris maintained at alow enough temperature to condense the propane. Furthermore after thepropane has been separated it must be again returned tov the evaporator.In the present case this is Adone by causing it to be vaporized and fedinto the condenser C2. The separator S, together with the associatedackets thus provides a compact and unitary assembly for accomplishingall of these unctions.

Since the drawings is only diagrammatic in nature it is obvious that inconstructing an apparatus in accordance with the principles of theinvention, various expedients may be resorted to and various changes maybe made in the arrangement and construction of the various parts withoutdeparting from the spirit of the invention. Various kinds of rectifiers,generators, condensers, etc., may be substituted for those shown andvarious types of pumps lor e'jectors substituted for the gas lift pump16.

As illustrating a somewhatdi'erent con- ,struction for carrying out theprinciples of the invention reference may be -had to Figthe differentabsorber structure, the condensure 2 in whichV the general arrangementand construction of the various parts of the apparatus is similarto thatof Figure lvbut in which a different form. of generator, separator andpumping means for the'absorption solution is illustrated. In this figurethe rec- -tifiers, condensers and evaporator are identical with those ofFigure 1 and need not be further described here. 'However,-because ofthe coil 29 and pipes 27 and 28 of Figure 1 of the copendingapfplication of Altenkirch,

Serial No. 99,890, led April 5, '1926, for absorption machines. As thisgas from the evaporator meets with the solution Ycoming through thelower portionvof pipe 141 connected with the outer tube of the heatexchanger 140, it causes this liquid tovrise through the coil 116 intothe separator S2. From the separator the solution flows out through thepipe 139 through the inner tube` of the heat exchanger 140, into theboiler-` through the pipe 115 and from there back to the outer coil ofthe heat exchanger through the pipes 123, a heating coil 144 and theconduit 142. Since the direction` of circulation is upward both in thegenerator and in the separator the circulationk is aided by thermo-Siphon action and by the generation of bubbles which pass upwardly inthe generator.

Essentially the separator S2 functions the same as separator S of Figure1, its lower portion being cooled by the cooling tank 145 and its. upperportions being heated by the coil 144. The directions of ilow of theabsorption solution through the separators are opposite in the twocases, however.

ince the pressure in the evaporator of Figure 2 must be somewhat higherthan that necessaryvin Figure 1, because of the greater liquid head tobe overcome in the separator, 4it is necessary that the pipes 27 and 28be long enouglrtopermit columns of liquid to form therein of sulicientheight to balance the head in the separator. For this reason thecondensers of Figure 2 must be a greater distaice above theevaporatorthan that necessary in Figure 1.

It is also necessary to charge the apparatus of Figure 2 with morepropane than that employed in the arrangement of Figure 1, since theseparator S2 vshould atall times, have enough liquid propane therein toextend from a level just below the coil 144 to a level near the top ofthe separator.

.It will be obvious'to those skilled in the art that various otherchanges may be made without departing from the spiritof the invention orthe scope of the annexed claims. For example the vessels may be made ofdiierent shapes and dimensions so long as they do not interfere with theintended circulation and liquid levels. It is also within the scope ofthe invention to control the circulation ofl the refrigerants or theabsorption solution by providing suitable' regulating valves in thevarious conduits and to control the' application of heat to thegenerator and absorber. This may, for example, necessitate the provisionof a conduit connected in parallel with the jacket 44 between the pipes23 and 42 with suitable valves for regulating the amount of warmsolution which flows through the jacket.

I claim 1 1. In a refrigerating system of the absorption type employinga plurality of refrigerants, the combination of a lgenerator forexpelling one refrigerant from an absorption solution, anabsorber-separator, means for feeding a vapor mixture .of saidrefrigerants into said absorber-separator, means for circulating theabsorption solution between said generator and said absorber-separatorto cause one refrigerant to absorbed and another-condensed in saidabsorber-separa- *torand a jacket surrounding a portion ofemploying tworefrigerants,

- 2. In an absorption 'refrigerating one refrigerant to be absorbed andthe other condensed in said vessel and means forcausing the solution topass around a portion of said separating vessel before it is passed intothe interior thereof to convey heat thereto from the generator andtherebyvaporize the condensed refrigerant therein.

l3. In a refrigerating system having a generator and an absorber andemploying two refrigerants, the method of vaporizing one refrigerantfrom an absorption solution in absorberseparator to vaporize thecondensed refrigeranttherein. n

Signed at North'Canton, in the county of Stark, and State of Ohio, this23rd dayof January, A. D., 1930.

STANLEY R. CUMMINGS.

said generator and another refrigerant from y its liquid phase in saidvabsorber whichl includes the steps of applying heat directlyV to saidgenerator, circulating absorption solution between said generator andsaid absorber and causing said absorption solution to give up heat to aportion of said absorber before mixing directly with the fluid therein.4. The method of producing refrigeration including the steps of feedingtwo diffe/rent refrigerants in liquid phase into an evaporator, from theevaporator into a separating vessel, causing one refrigerant to beabsorbed in an absorption liquid and the other tobe condensed in saidvessel, separating the condensed'refrigerant from the absorptionsolution by gravity, conveying the enriched absorption solution to agenerator, applying heat to said generator to drive olf the absorbedrefrigerant and conveying the weakened absorption solution back to theabsorber while causing a transfer of heat from the weakened absorptionsolution to the Huid in the Vabsorber as the weakened absorptionsolution passes on its way to the absorber to thereby vaporize therefrigerant which has been condensed in said absorber.

5. In an absorption refrigerating"system employing two refrigerants, thecombination of an evaporator adapted to cause the two refrigerants toevaporate, an absorbeksepa; rator, a generator adapted to expel one ofsaid refrigerants from an absorption solu.- tion and means forcirculating absorption solution between said absorber-separator and saidgenerator to cause one refrigerant to be absorbed and the othercondensed in said absorber-separator, `said circulating means includinga device for causing the absorption solution to pass in heat transferrela-1 tion with a portion of said absorber-separator before it passesinto direct contact with conducting thevaporized refrigerant A the iuidstherein and thereby transfer heat from said generator to a portion ofsaid

